Specificity of bacteriophage ST1 to the other bacterial strains was examined by the spot test method. Of all 18 bacterial strains used in this experiment, only Shigella dysentariae (type1) DMST 2137 and Salmonella Typhi DMST 5784 were susceptible to the bacteriophage as shown in Table 1. On the other hand, the rest of the tested bacterial strains used in this study were not sensitive to the bacteriophage. Since the lytic activity of bacteriophage ST1 was not limited only to its specific host S. Typhimurium ATCC 13311, it could be considered as a bacteriophage with a board host range.